FBA vs FBM: Which One Costs Less?
The honest answer: it depends on your size tier and carrier rate — which is why guessing loses to computing. The calculator runs both modes on the same numbers side by side.
| Dimension | FBA | FBM |
|---|---|---|
| Fulfillment cost | Fixed by size tier (estimate-editable) | Your negotiated carrier rate |
| Storage | Amazon warehouse per-unit monthly | Your own shelf space (often invisible — still count it) |
| Returns | Allowance on cost; auto-handled | You handle shipping + restocking |
| Plan requirement | Individual or Professional | Individual or Professional |
| Buy Box tendency | Stronger for Prime-eligible offers | Weaker without Prime |
| Hidden costs | Long-term storage, low-inventory fees | Packing materials, time, support |
Rules of thumb that survive contact with numbers
- Small and light wins on FBM more often than people think — a letter-sized item shipping for $3 beats a small-parcel FBA tier once storage is added.
- Heavy or bulky items often lose money on FBA tiers — run the extra-large parcel estimate before committing inventory.
- Slow movers get punished by storage months — if a SKU sits 4+ months, FBA storage quietly eats the margin you calculated for month one.
- Buy Box pressure is real — pure cost math can favor FBM while conversion still favors Prime. Compute the cost gap, then price the gap you'd accept for velocity.
Run both on your real numbers
Enter the product once, then flip the FBA/FBM switch — net profit, margin and the fee stack update instantly for both modes.
Compare FBA vs FBM now